Nonaqueous photographic emulsions



3,003,879 Patented Oct. 10, 1961 iice 3,003,879 NONAQUEOUS PHOTOGRAPHICEMULSIONS William J. Priest and Ernest J. Perry, Rochester, N.Y.,assignors to Eastman Kodak Company, Rochester, N. a corporation of NewJersey No Drawing. Filed Jan. 8, 1959, Ser. No. 785,567 5 Claims. (Cl.96-414) This invention relates to photographic emulsions, the liquidportion of which is an organic solvent and the carrier for the silverhalide is a carboxy-lated polyvinyl acetal or butyral, the salts ofwhich are soluble in water and the acid forms of which are soluble incertain organic solvents.

Photographic emulsions are usually prepared by precipitating silverhalide grains in an aqueous solution of a peptizer, such as aWater-soluble synthetic polymer like polyvinyl alcohol. Often theresulting silver halide is subjected to a series of operations topromote grain growth and to remove the potassium nitrate formed duringthe silver halide precipitation, after which the grains are dispersed inan aqueous solution of a vehicle prior to coating on a film base.

In the case of special applications such as for facilitating the rapiddrying of a photographic emulsion upon a support the silver halide andthe vehicle therefor has been dispersed in organic solvents. Variouspolymeric substances have been thought of for vehicles in thisconnection, but many such materials although soluble in organic solventsare insoluble in water. These polymers Would be unsuitable as peptizersfor preparing silver halide dispersions inasmuch as the startingmaterials ordinarily employed i.e. silver nitrate, potassium bromide andpotassium iodide are generally insoluble in organic solvents.Hydrophobic water-insoluble polymers do not swell appreciably in waterand, hence, offer resistance to penetration by aqueous solutions.Emulsion coatings prepared from such polymers would be resistant topenetration by aqueous photographic developer and fixer solutions. Somepolymers which are soluble both in 1 water and organic solvents do notreadily lend themselves to washing out of the soluble salts (formed inthe preparation of the silver halide) by a temporary coagulation of thesilver halide grains.

One object of our invention is to provide nonaqueous photographicemulsions in which the carrier for the silver halide is a carboxylatedpolyvinyl acetal or carboxylated polyvinyl butyral, which is Watersoluble in the salt form and soluble in certain organic solvents in thefree-acid form. Another object of our invention is to provide aprocedure for the preparation of nonaqueous photographic emulsions inwhich the polymer employed as the peptizer for the silver halide maycorrespond to that which is employed as the protective colloid in thenonaqueous emulsion which is ultimately formed. Other objects of ourinvention will appear herein.

We have found that nonaqueous photographic emulsions can be convenientlyprepared by means of carboxylated polyvinyl acetals or carboxylatedpolyvinyl butyrals containing at least 2 mole percent of carboxyl bypreparing the silver halide dispersion in water solution using the saltform thereof and from this preparing the emulsion proper using thefree-acid form of the polymer which is soluble in organic solvent. Wehave found that after the silver halide dispersion has been formed usingthe salt form of the polymer, the dispersion may be coagulated and thegrains thus obtained may be dried without any interference with theirdispersion in organic solvents. The nonaqueous photographic emulsions inaccordance with our invention may be prepared using either dioxane,isopropanol, acetone or dimethoxyethane as the liquid portion of theemulsion. In the use of the carboxylated polyvinyl acetals the materialemployed should contain 60-87 mole percent of polyvinyl acetal and atleast 4 mole percent carboxyl should be present therein. In the case ofthe carboxylated polyvinyl butyrals there should be 5075 mole percent ofpolyvinyl butyral and the minimum carboxyl content should be 4 molepercent if the polyvinyl butyral content is 50%, and 17 mole percent ifthe polyvinyl butyral content is in the vicinity of The preparation ofcarboxylated polyvinyl acetals and butyrals may be in accordance withthe method described in US. Patent No. 2,828,289 of John W. Mench.

The nonaqueous emulsions in accordance with our invention are preparedby first preparing an aqueous dispersion of silver halide in an aqueoussolution of a water soluble salt of carboxylated polyvinyl acetal orbutyral. After the dispersion has formed, the silver halide grains arecoagulated by the addition of acid to reduce to a pH within the range of3-4.5. The coagulum thus formed is separated from the liquid and ispreferably washed, such as with distilled water and is dried. Thecoagulum is then dispersed in an organic liquid containing in solutionthe free acid form of carboxylated polyvinyl acetal or butyral. Ifdesired, in the preparation of the emulsion, ripening of the silverhalide grains may be employed and sensitizers or other additives may beadded to the emulsion composition. For instance, if desired, a hardenersuch as bis(2,3-epoxypropoxyethyl)ether may be incorporated in an amountof 4% based on the weight of the polymer. Any suitable hardener,however, may be added to the composition. Instead of dispersing thesilver halide in a solution of carboxylated polyvinyl acetal or butyralit may be incorporated in a solution of a mixture of one of thosematerials with a polyvinylacetal providing /2 or more of the polymer isthe carboxylated product. In cases where permeability of the emulsionlayer is not critical even a higher proportion of the polyvinyl acetalmay be used.

The carboxylated polyvinyl acetal or carboxylated polyvinyl butyral maybe prepared by reacting upon a polyvinyl acetal or preferably in theform of its anhydride. Although the phthaloylated material has beenfound to be quite useful other dicarboxylic acid groups such assuccinyl, maleyl, diglycolyl or the like might be incorporated in thepolyvinyl compound such as by reacting the polyvinyl compound with thecorresponding anhydride. ous photographic emulsions obtained inaccordance with our invention may be coated on to a suitable supportforming layers which are characterized by being permeable to aqueousalkaline photographic processing solutions that convert the waterpermeable form. The polymer which is employed as the carrier for thesilver halide should be present in the emulsion in an amount at leastequal to the amount of the silver halide which is present therein. Themere use of carboxylated polyvinyl acetal in an amount only butyral withany dicarboxylic acid The nonaquepolymer vehicle to thehydrophilicsufiicient to act as a color former in the emulsion does notserve as the vehicle for the silver halide in the nonaqueousphotographic emulsion.

The following examples illustrate our invention:

Example 1 Two solutions were prepared as follows:

A. 14.1 ml. of 2 molar silver nitrate 2.2 ml. of ammonium hydroxide(specific gravity 13.7 ml. of water at a temperature of 17 C.

1.6 grams of the ammonium salt of phthaloylated polyvinyl acetalcontaining 72.5 mole percent of polyvinyl acetal, 21.9 mole percent ofpolyvinyl alcohol, and 5.6 mole percent of polyvinyl phthalate 31.4 ml.of water 16.6 ml. 2 molar potassium bromide 0.8 ml. of 0.5 molarpotassium iodide Temperature: 17 C.

Solution A was run into solution B over a period of approximately 2minutes, solution B having been stirred continuously. A silver halidedispersion was obtained. The silver halide grains therein werecoagulated by the addition of 100 ml. of 20% aqueous acetic acid to thedispersion. The coagulum which formed was separated from the liquidportion and was washed by 3 consecutive washes each with 1 liter ofdistilled water following which the coagulum was dried at 65 C. for 18hours. The dried coagulum was suspended in 23.6 grams of dioxane withheating and stirring. This suspension was then dispersed in 76.4 gramsof a 7% solution in dioxane of the free-acid form of a phthalatedpolyvinyl acetal described under B above. The emulsion was coated ontocellulose triacetate film base at 19 C., and the coating thus formed wasdried by the application of warm dry air. The emulsion coating waspermeable to alkaline photographic developer and fixer solutions.

Example 2 Emulsion making procedure as described in Example 1 wasfollowed except that isopropanol was used as the organic solvent and thepolymeric peptizer and vehicle was the salt and free-acid formrespectively of a phthaloylated polyvinyl butyral containing 50.0 molepercent polyvinyl butyral, 38.3 mole percent polyvinyl alcohol, 7.5 molepercent polyvinyl phthalate, and 4.2 mole percent polyvinyl acetate, andsolutions A and B were kept at 26 C. instead of 17 C. The emulsion wascoated onto a cellulose triacetate film base and the coating was driedby a current of warm dry air. It was found to be permeable to alkalinephotographic developer and fixer solutrons.

Example 3 Emulsion making procedure as described in Example 1 wasfollowed except that acetone was used as the organic solvent and thepolymeric peptizer and vehicle was the salt and free-acid formrespectively of a copolymer containing 75 mole percent ethyl acrylateand 25 mole percent acrylic acid and solutions A and B were kept at 26C. instead of 17 C. The emulsion was coated onto a polyethyleneterephthalate film base and the coating was dried by a current of warmdry air. It was found to be permeable to alkaline photographic developerand fixer solutions.

Coatings prepared from organic solvent solutions of the free-acid formof carboxylated polyvinyl acetal or butyral differ from coatingsprepared from aqueous solutions of salts of those polymers in that theyshow lower swelling values in photographic processing solutions andlower regain values at higher relative humidity. For instance, a coatingprepared from a dioxane solution of Q. the free-acid form of phthalatedpolyvinyl acetal was compared with a coating prepared from an aqueoussolution of the ammonium salt of phthaloylated polyvinyl acetal. Thefollowing values were obtained:

The flex life and abrasion resistance of coatings of the nonaqueousphotographic emulsion coatings were equivalent to those from coatingsmade from the aqueous solution.

Some of the materials described herein are useful as vehicles foraqueous silver halide photographic emulsions. Thus, aqueous dispersionsof carboxylated polyvinyl acetals containing 60 to 87 mole percent ofpolyvinyl acetal and 1 to 12 mole percent of polyvinyl phthalate gel asthe temperature is raised, which facilitates rapid high temperaturedrying. When the polyvinyl acetal concentration is at the low end ofrange, e.g., 60 mole percent, the polyvinyl phthalate content must beheld fairly critically between 2 and 4 mole percent to insure usefulheat gelling properties; at the high end, e.g., around 87 mole percent,the polyvinyl phthalate concentration can vary considerably, say from 2to 12 mole percent.

Representative compositions are tabulated below:

MOLE PERCENT CONCENTRA- TIONS IN TYPICAL HEAT SET- TING CARBOXYLATEDPOLY- VINYL ACETALS The photographic emulsions used in practicing ourinvention are of the developing-out type.

The emulsions can be chemically sensitized with sulfur compounds such asthose described in Sheppard U.S. Patent 1,574,944; Sheppard and PunnettU.S. Patent 1,623,- 499; and Sheppard and Brigham U.S. Patent 2,410,689.

The emulsions can also be treated with salts of the noble metals such asruthenium, rhodium, palladium, iridium, and platinum. Representativecompounds are ammonium chloropalladate, potassium chloroplatinate, andsodium chloropalladite, which are used for sensitizing in amounts belowthat which produces any substantial fog inhibition, as described inSmith and Trivelli U.S. Patent 2,448,060, and as antifoggants in higheramounts, as described in Trivelli and Smith U.S. Patents 2,566,245 and2,566,263.

The emulsions can also be chemically sensitized with gold salts asdescribed in Waller, Collins, and Dodd U.S. Patent 2,399,083 orstabilized with gold salts as de- 1 scribed in Damschroder U.S. Patent2,597,856 and Yutzy and Leermakers U.S. Patent 2,597,915. Suitablecompounds are potassium chloroaurite, potassium aurithiocyanate,potassium chloroaurate, auric trichloride and 2- aurosulfobenzothiazolemethochloride.

The emulsions can also be chemically sensitized with reducing agentssuch as stannous salts (Carroll, U.S.

Patent 2,487,850), polyamines, such as diethylene triamine (Lowe andJones, U.S. Patent 2,518,698), polyamines, such as spermine (Lowe andAllen, U.S. Patent 2,521,925), or bis(fi-aminoethyl)sulfide and itswatersoluble salts (Lowe and Jones, U.S. Patent 2,521,926).

The emulsions can also be optically sensitized with cyanine andmerocyanine dyes, such as those described in Brooker U.S. Patents1,846,301; 1,846,302; and 1,942,- 854; White U.S. Patent 1,990,507;Brooker and White U.S. Patents 2,112,140; 2,165,338; 2,493,747; and2,739,- 964; Brooker and Keyes U.S. Patent 2,493,748; Sprague U.S.Patents 2,503,776 and 2,519,001; Heseltine and Brooker U.S. Patent2,666,761; Heseltine U.S. Patent 2,734,900; Van Lare U.S. Patent2,739,149; and Kodak Limited British Patent 450,958.

The emulsions can also be stabilized with the mercury compounds ofAllen, Byers, and Murray U.S. Patent 2,728,663; Carroll and Murray U.S.Patent 2,728,664, and Leubner and Murray U.S. Patent 2,728,665; thetriazoles of Heimbach and Kelly U.S. Patent 2,444,608; the azaindenes ofHeimbach and Kelly U.S. Patents 2,444,605 and 2,444,606; Heimbach U.S.Patents 2,444,- 607 and 2,450,397; Heimbach and Clark U.S. Patent2,444,609; Allen and Reynolds U.S. Patents 2,713,541 and 2,743,181;Carroll and Beach U.S. Patent 2,716,062; Allen and Beifuss U.S. Patent2,735,769; Reynolds and Sagal U.S. Patent 2,756,147; Allen and SaguraU.S. Patent 2,772,164, and those disclosed by Birr in the Z. wiss. Phot.47, 2 (1952); the disulfides of Belgian Patent 569,317; the quaternarybenzothiazolium compounds of Brooker and Stand U.S. Patent 2,131,038 orAllen and Wilson U.S. Patent 2,694,716 (e.g.,decamethylene-bisbenzothiazolium perchlorate); and the zinc and cadmiumsalts of Jones U.S. Patent application Serial No. 493,047.

The emulsions may also contain speed-increasing compounds of thequaternary ammonium type of Carroll U.S. Patent 2,271,623; Carroll andAllen U.S. Patent 2,288,226; and Carroll and Spence U.S. Patent2,334,864; and the polyethylene glycol type of Carroll and Beach U.S.Patent 2,708,162.

In the preparation of our emulsions various silver salts may be used asthe sensitive salt such as silver bromide, silver iodide, silverchloride, or mixed silver halides such as silver chlorobromide or silverbromoiodide. The emulsion vehicles described herein may be used inemulsions intended for color photography, for example, emulsionscontaining color-forming couplers or emulsions to be developed bysolutions containing couplers or other color-generating materials,emulsions of the mixed-packet type, such as described in Godowsky U.S.Patent 2,698,- 794 or emulsions of the mixed-grain type, such asdescribed in Carroll and Hanson U.S. Patent 2,592,243. The vehicles canalso be used in emulsions which form latent images predominantly on thesurface of the silver halide crystal or in emulsions which form latentimages predominantly inside the silver halide crystal, such as thosedescribed in Davey and Knott U.S. Patent 2,592,250.

The vehicles may also be used in emulsions intended for use in diffusiontransfer processes which utilize the undeveloped silver halide in thenonimage areas of the negative to form a positive by dissolving theundeveloped silver halide and precipitating it on a receiving layer inclose proximity to the original silver halide emulsion layer. Suchprocesses are described in Rott U.S. Patent 2,352,014 and Land U.S.Patents 2,584,029; 2,698,- 236 and 2,543,181; and Yackel et al. U.S.Patent application Serial No. 586,705. They may also be used in colortransfer processes which utilize the diffusion transfer of an image-wisedistribution of developer, coupler or dye, from a light-sensitive layerto a second layer, while the two layers are in close proximity to oneanother. Color processes of this type are described in Land U.S. Patents2,559,643 and 2,698,798; Land and Rogers Belgian Patents 554,933 and554,934; International Polariod Belgian Patents 554,212 and 554,935;Yutzy U.S. Patent 2,756,142, and Whitmore and Mader U.S. Patentapplication Serial No. 734,141.

In the preparation of the silver halide dispersions employed forpreparing silver halide emulsions there may be employed as thedispersing agent for the silver halide in its preparation, gelatin orsome other colloidal material such as colloidal albumin, a cellulosederivative, or a synthetic resin, for instance, a polyvinyl compound.

Combinations of these antifoggants, s'ensitizers, 'etc., may be used.

We claim:

1. A method of making nonaqueons photographic emulsions which comprisesreacting silver nitrate and Water soluble halide in an aqueous solutionof a peptizer selected from the group consisting of the water solublesalts of carboxylated polyvinyl acetals containing 6087 mole percentpolyvinyl acetal and at least 4 and not more than 40 mole percent ofcarboxyl, and the water soluble salts of carboxylated polyvinyl butyralscontaining 50-75 mole percent polyvinyl butyral, the minimum carboxylcontent being within the range of 4-17 mole percent and the maximumcarboxyl content being mole percent minus the mole percent of polyvinylbutyral contained therein, coagulating the dispersion thus formed byadjusting the pH to a value within the range of 34.5, separating thesilver halide coagulum and drying, followed by dispersing the coagulumin a solution of the free acid form of the polyvinyl compound in asolvent selected from the group consisting of dioxane, isopropanol,dimethoxyethane and acetone, whereby a silver halide photographicemulsion composition is obtained.

2. A method of preparing a nonaqueons photographic emulsion whichcomprises reacting silver nitrate with a water soluble ha'lide in anaqueous solution of a water soluble salt of a carboxylated polyvinylacetal containing 60-87 mole percent polyvinyl acetal and at least 4 andnot more than 40 mole percent of carboxyl, adjusting the pH to a valuewithin the range of 3-4.5 to coagulate the silver halide for-med,separating the silver halide coagulum, and drying followed by dispersingthe coagulum in a solution of the free acid form of the carboxylatedpolyvinyl acetal in an organic solvent selected from the groupsconsisting of dioxane, isopropanol, dimethoxyethane and acetone, wherebya silver halide photographic emulsion is obtained.

3. A method of preparing a nonaqueons photographic emulsion whichcomprises reacting silver nitrate with a water soluble halide in anaqueous solution of water soluble salt of a carboxylated polyvinylbutyral containing 50-75 mole percent of polyvinyl butyral, the minimumcarboxyl content being within the range of 4-17 mole percent and themaximum carboxyl content being 100 mole percent minus the mole percentof polyvinyl butyr-a'l contained therein, whereby a silver halidedispersion is formed, adjusting to a pH of 3-4.5 whereby the silverhalide is coagulated, separating the resulting coagulum from the liquidportion of the mass, and drying followed by dispersing the coagulum in asolution of the free acid form of the carboxylated polyvinyl butyral inan organic solvent selected from the group consisting of dioxane,isopropanol, dimethoxyethane and acetone, whereby a silver halidephotographic emulsion is obtained.

4. A method of preparing a nonaqueons photographic emulsion whichcomprises reacting silver nitrate with a water soluble halide in anaqueous solution of an ammonium salt of phthaloylated polyvinyl acetalcontaining 60-87 mole percent polyvinyl aceta-l and atleast 4 and notmore than 40 mole percent of carboxyl, coagulating the silver halidegrains thus formed by adjusting to a pH within the range of 34.5separating the thus formed coagulum, washing and drying and dispersingthe coagulum in a solution of the free acid form of the phthaloylatedpolyvinyl acetal in dioxane, whereby a silver halide photographicemulsion is obtained.

5. A method of preparing a nonaqueons photographic emulsion whichcomprises reacting silver nitrate with a water soluble halide in anaqueous solution of the ammonium salt of phthaloylated polyvinyl butyralcontainpanol whereby a silver halide photographic emulsion is obtained.

References Cited in the file of this patent UNITED STATES PATENTS Mochelet al. July 3, 1956 Mench Mar. 25, 1958 Dann et a1. Apr. 14, 1959

1. A METHOD OF MAKING NONAQUEOUS PHOTOGRAPHIC EMULSIONS WHICH COMPRISESREACTING SILVER NITRATE AND WATER SOLUBLE HALIDE IN AN AQUEOUS SOLUTIONOF A PEPTIZER SELECTED FROM THE GROUP CONSISTING OF THE WATER SOLUBLESALTS OF CARBOXYLATED POLYVINYL ACETALS CONTAINING 60-87 MOLE PERCENTPOLYVINYL ACETAL AND AT LEAST 4 AND NOT MORE THAN 40 MOLE PERCENT OFCARBOXYL, AND THE WATER SOLUBLE SALTS OF CARBOXYLATED POLYVINYL BUTYRALSCONTAINING 50-75 MOLE PRECENT POLYVINYL BUTYRAL, THE MINIMUM CARBOXYLCONTENT BEING WITHIN THE RANGE OF 4-17 MOLE PERCENT AND THE MAXIMUMCARBOXYL CONTENT BEING 100 MOLE PERCENT MINUS THE MOLE PERCENT OFPOLYVINYL BUTYRAL CONTAINED THEREIN, COAGULATING THE DISPERSION THUSFORMED BY ADJUSTING THE PH TO A VALUE WITHIN THE RANGE OF 3-4.5,SEPARATING THE SILVER HALIDE COAGULUM AND DRYING, FOLLOWED BY DISPERSINGTHE COAGULUM IN A SOLUTION OF THE FREE ACID FORM OF THE POLYVINYLCOMPOUND IN A SOLVENT SELECTED FROM THE GROUP CONSISTING OF DIOXANE,ISOPROPANOL, DIMETHOXYETHANE AND ACETONE, WHEREBY A SILVER HALIDEPHOTOGRAPHIC EMULSION COMPOSITION IS OBTAINED.